<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>
  <script>
    let key = prompt('请输入一个星期数，就能将对应的英文的星期打印出来')
    switch (key) {
      case '星期一':
        document.write('mondey')
        break;
      case '星期二':
        document.write('tuesday')
        break;
      case '星期三':
        document.write('wednesday')
        break;
      case '星期四':
        document.write('thursday')
        break;
      case '星期五':
        document.write('firday')
        break;
      case '星期六':
        document.write('saturday')
        break;
      case '星期天':
        document.write('sunday')
        break;

      default:
        break;
    }
  </script>
</body>

</html>